Keith Hennessey and Jonathan Chait have gone two rounds in an argument about Bush, Obama, and responsibility for current and future deficits. (Here are the links: Hennessey, Chait, Hennessey again, and Chait again.) I think Chait has scored some points, but chiefly on secondary issues, while ignoring Hennessey’s most important arguments.

To my mind these are: 1) “Given that we now know that the January 2001 economic and surplus projections were wrong, it is misleading for Team Obama to use those knowingly incorrect projections to describe the effects of Bush Administration policies.” 2) Bush’s prescription-drug benefit needs to be placed in a political context in which both parties favored a big entitlement expansion without offsetting tax hikes or spending cuts, and in which the Democrats wanted a more expensive entitlement. 3) Obama’s policies increase the deficit compared to pre-existing law.

One possible response to point 2 would be that Bush should have shown more political leadership; but if we’re going to dismiss political constraints we should do so evenhandedly, and Obama’s push to extend some of Bush’s tax cuts has to be counted toward his contribution to the deficit.